Method of sealing crevices in rock formations



G. W. CHRISTIANS. METHOD OF 'SEAL ING CREVICES IN ROCK FORMATIONS.

APPLICATION FILED JUNE 9. I919.

Patented Jan. 6, 1920;

i E rarns r'rn GEORGE W. CHRISTIANS, OF CHAT'IANOOGA, TENNESSEE.

- METHOD OF SEALING CREVICES IN ROCK-FORMATIONS.

Specification of Letters Patent.

Patented J an. 6, 192%.

Application filed June 9, 1919. Serial No. 302,795;

cool, through a suitably heated pipe into the rock containing thecrevices or cavities.

' After reaching the rock formation, the sealing material sure and thenbecomes cool and practically solid, thus filling the crevices andeffectually sealing said crevices against the passage of water and thelike.

I have found from practical operations that a number of differentmaterials, such as sulfur, asphalt or coal tar pitch, may be a used, butI believe that unadulterated asphalt'is the best [material for theprocess.

It has heretofore been proposed'to introduce bitumen, pitch and sulfurinto'creviced rock for the purpose of sealing the interstices but themethod of introducing such materials is essentially diflerent from myprocess and it has never been used to commercial advantage.

Cement has also been used prior to my invention'for filling rockcrevices and it may be of assistance at this stage to point out theadvantages of my method over the cement grouting method. First, mymethod can-be successfully employed, for sealing crevices or a cave ofconsiderable size, through which water is flowing at relatively highvelocity, without loss of material by washing. In grouting, greatquantities of cement are oftenwashed away and wasted before a closure iseffected and then it is frequently impossible to determine whether thecrevice is sealed or whether the drilled holehas be-' untll a highresisting pressurehas been enters the crevices under presand is strongenough reached a definite assurance'is obtained that all spaces adjacentto the pi e line are filled. Grouting can only be effective at one pointat a time and when the introduction of the cement at this point isfinished, a new hole must be drilled. Third, with my method, after theWork is completed at any particular hole, the pipe together with aportion of the heating means are left embedded in the sealing material,so that if it is considered desirable at some future time (several yearslater if necessary) more material may be forced into the same hole' bymerely making the proper connections with the pipe and heating means.:lhen after'heating for a few minutes, additional material may beintroduced, the same as if the .original operation had never beenhalted. When grouting, on

the other hand, a stoppage of only a few minutes allows the cement toset in the hole and consequently no more cement can be inserted. Owingto this solidifying of the cement, a new hole must be drilled if it isde- I sired to continue the work.

Before proceeding with a detail description of the process, it may bewell to mention some practical observations had during recent successfuldemonstrations of my method. It has been found in practice that pitchand asphalt are very poor conductors of heat and this fact very greatlyassists the operation. In my process, an electrical conducting wireextends through the pipe for the purpose of maintaining the material inheat ed condition during its passage through the pipe, and the asphaltor pitch which sur-' rounds the wire, efiectually insulates the a wirefrom the pipe, both electrically and' thermally, so that while the pipemay be cold yet very little heat is required to maintain a fluid passageadjacent the wire. As soon as the sealing material leaves the pipe andtouches the Water in the crevicethe surface of the material hardens into.a tough skin, but the heat conductivity is so poor, that the interiorof the material remains hot I and fluid. The hardened skin forms a toughsack which clings to the opening in the pipe to resist the pressure of pa considerable velocity of water or the like,

but the inside of the sack and a connection between the'opening in thepipe and the inside of the sack remains fluid as long as a continuousflow is maintained, so that the sack can be expanded indefinitely,unless obstructed, with very little pressure. This enmelting point, suchas unadulterated asphalt, may be successfully used.

With a view of more clearly setting forth the invention, reference maybe had to the accompanying drawing,which illustrates a .part oftheapparatus forming the subject matter of an application filed of evendate herewith and bearingSerial Number 302,796.

In the drawing: Figure 1 is a diagrammatic view of the apparatusillustrating the manner of introducing the heated sealing material intothe rock crevices under pressure. I

Fig. 2 1s a detail vlew of the materlal conductin pipe.

In tile drawing 1 represents a supply tank -or reservoir in which thehot sealing ma terial such as pitch or asphalt is stored. A pipe 2connects this tank with a heating chamber 3 in.which the material iskept heated by means of suitable burners 4. A .pump 5 is located in the.heating chamber and is maintained in heated conditionby being submergedin the sealing material contained in the chamber 3. The pum is drivenfrom a suitable power means not shown) through the medium of the belt 6and it is adapted to draw the hot material from the chamber 3 and forcethe same with considerable pressure into the pipe 7. 'The pipe 7 isprovided with a suitable pressure gage 8 and located within the pipe isa heating wire 9, which is connected to an electric supply line wire 10;One end of the wire is connected by a suitable yielding device, such asa coil spring 11, to a fixed or stationary point" 12, and the other endof the wire is fixed to a terminal of connector 29 which bears against.an insulated plug 13, carried,

by one arm of a cross-shaped pipe fitting 14.. The spring 11 maintainsthe wire 9 taut in the pipe 7 The other wire 15 of the supply line is inelectrical connection with the pipe 7.

A second pipe-16 is connected to the fitting 14 and is extended downinto, a previously drilled hole 17, which communicates with the crevicesor cracks 18 that are to be filled or sealed. The pipe 16 is made up ofanumber of sections 19 connected together by couplings 20 and it carriesat its lower end a point 21; As will be seen from the drawing, thesections of the pipe 16, which are adjacent the crevices 18 are providedWith a series of apertures 22 and located between the adjacent ends ofthe pipe sections 19 are insulating washers. 23, which aid inmaintaining an electric circuit through the pipe 16. This wire 24 isconnected at its lower end 25 to the point 21 and its upper portionextends with a free lit through an which has its upper end fixed to astationary support 28,- and this spring tends to maintain the wire 24taut and out of electrical connection with the inner surface of the pipe16. An electric conducting wire 29 connects the wires 9 and 24 together,so that v the electric current from the line wire 10 passes through theWires 9, 29 and 24 in the I order named to the point 25, then along thepipes 16 and 7 back to the line wire 15. It will-be understood thatthewires 9 and 24 are highly heated by the electric current and that theymaintain the interiors of the pipes .7 and 16 in heated condition, sothat sealing material passing through said pipes will be kept in heatedcondition until it passes out through the apertures' inthe pipe 16.

With the abovedescribed apparatus my method is carried out as follows: Asuitable sealing material, which is fluid when heated but nearly solidand extremely viscous when cool, is placed in thevreservoir 1. A numberof different materials such as sulfur, asphalt or coal tar pitch may beemployed but it is necessary that the material have a moderately lowmelting point, that it be an insulator of electricity, and that it benot absolutely solid and non-fluid'when cohled. Unadulterated as halt isprobably the most practical material It may be desirable to vary theconsistency of the ma' terial so that when cooled it may be made more orlessfiliid. -With asphalt, this can be done-by the addition of a smallpercentage of crude oil. The character of the ma terial used dependsupon the conditions encountered. It is necessary that the materialbestifi enough to resist any pressure tending to push it out of thecrevice (such as the head water of a dam) but it must be fluid enough sothat a moderate hydraulic pressure will force it the necessary distanceinto the crevice or crevices.

'through the apertures in the pipe 16, the

material acquires .a thick skin, and the heated material passing fromthe pipe enters this skin and maintains the interior of the skin in hotfluid condition while the skin is being expanded by the pressure on thematerials After the crevices are filled, the electric current is cut oiland the material is permitted to cool and solidify. Then the fitting 14is disconnected from the pipe 16 that various changes,

.of any depth.

and connected to another pipe which is used in operating on a secondhole.

The operation of filling a crevice may be continuous or intermittent andas many stoppages may occur as" are desirable. When shut down, theelectric current is cut off and the material in the pipe line is insubstantially solid condition. When starting up again, the current isturned on and in a few minutes the material in the pipe line will beheated and liquefied and ready to be pumped.

The pipe lines can be made of One inch extra heavy pipe, cut in fivefoot lengths with a coupling containing a, lava insulating washerbetween each length of pipe. The pump may be located at any convenientplace and the material piped for any reasonable distance to the openingof the drill hole and down the hole to the crevices. Where the pipe linepasses through the crevices or porous formation, it is preferablyperforated at 22 with three-quarter inch holes at three inch centers sothat the material can flow out into the opening. The hot Wire passingdown through the pipe maintains a fluid passage so that the pressure isequalized throughout its whole length, and one material is free toexpand at the points of least resistance. Where it is necessary tochange the direction of the pipe line, suitable insulating fittings 14,a connector for the wires 29 and strong and 2-7 to keep the wire taut,must be provided.

The holes down which the pipe line runs may be drilled with diamond orshot core drills or with churn type drills, and need only be two inchesin diameter, and can be For waterproofing the foundation of a dam, theyshould be spaced at regular intervals at such a distance that thematerial expanded into a crevice from one. will meet the asphaltexpanded from the 'next, and so make a complete seal. The holes may bedrilled at twelve foot centers and the material pumped into them oneafter another.

, While I have described the most essential details of-my method, itwill be understood that the steps of the method need not be followed inthe order named. I am aware modifications and differentiations may bemade inthe method without departing from the spirit of the invention asoutlined in the followmg claims.

What I claim and desire to secure by Letters Patent is 1. The method ofsealing crevices in fissured rock formations consisting in extending aconduit to the place where a. crevice occurs, forcing a material whichis fluid when heated but nearly solid when cool,

tension springs 11 through said conduit and into said crevice,generating heat within the conduit, and utilizing the heat generatedforv maintaining the material in heated condition during its passagethrough said conduit and into said crevice.

2. A method of sealing a crevice under ground, which consists indrilling a hole to the place where the crevice occurs, placing a conduithaving a perforated wall in said hole with the perforations adjacentsaid crevice, forcing a, material which is fluid when heated and nearlysolid when cool, through said conduit and perforations, and intosaidcrcvice, generating heat within the conduit, and utilizing the heatgenerated for maintaining the material in fluid and heated conditionduring its travel through said conduit and perforations and into saidcrevice.

3. A method of sealing crevices in fissured rock formations, winchconslsts in extend in a pipe provided with apertures into the a rockformation and arranging the perforations adjacent said crevices,introducing a material, which is fluid when heated and nearly solid whencool, under pressure through said pipe and perforations into saidcrevices. generating heat Within the. pipe, and utilizing the heatgenerated for maintaining the materialin heated fluid condition duringits travelthrough said pipe and perforations into said crevices.

4. A method of sealing a crevice in a fissured rock formation,consisting in drilling a hole through the rock tosaid crevice, insertinga pipe having a perforated portion into said hole and arranging theperforations of the pipe adjacent the crevice, forcing under pressure amaterial, which is fluid when heated and nearly solid when cool, throughsaid pipe and perforations into said crevice, generating heat within thepipe, and utilizing the heat generated for maintaining said material influid condition during its' passage through the pipe and perforationsinto said crevice. I

5. A method of sealing interstices in under ground'formations, whichconsists in drilling a hole to the point Where the inter stices occur,"inserting a perforated pipe'into said hole and arranging theperforations of the pipe adjacent said interstices, forcing asphalt influid condition and under pressure through said pipe and perforationsand into said interstices, generating heat within the pipe,utilizlng'the, eat generated for mainta ning the asphalt in heatedcondition until it is lodged in said interstices, and permitting theasphalt to 0001.

In testimony whereof I have hereunto affixed my signature. v GEORGE W.CHRISTIANS.

